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Abstract Objective: MicroRNAs play crucial roles in the pathogenesis of cancers. MiRNA-218-5p may act as either an oncogene or a tumor suppressor, but its role in the pathogenesis of Breast Cancer (BC) remains unclear. Methods: Infiltrative breast ductal carcinoma as well as corresponding adjacent normal samples were collected from 30 patients. Mimics and inhibitors of miRNA-218-5p or corresponding negative controls were transfected into BC cells. miRNA-218-5p expression was detected by quantitative PCR. The effects of miRNA-218-5p on the malignant behaviors of BC were assessed. Dual-luciferase reporter assay was employed to evaluate the binding of miRNA-218-5p to LRIG1. Results: BC tissues showed higher miRNA-218-5p expression as compared to the adjacent normal tissues. Ectopic miRNA-218-5p expression accelerated the cell cycle, cell growth and migration of BC, while repressed cell apoptosis. Interestingly, ectopic miRNA-218-5p expression down-regulated LRIG1 expression, and miRNA-218-5p could bind to LRIG1. Also, our study indicated that miRNA-218-5p up-regulated ErbB2 and EGFR expression by targeting LRIG1, suggesting that the LRIG1-mediated signaling pathway contributed to the pro-tumor effects of miRNA-218-5p on BC. Conclusion: MiRNA-218-5p up-regulates ErbB2 and EGFR expression by suppressing LRIG1 expression, thus promoting the malignant behaviors of BC. miRNA-218-5p may exert a pro-tumor effect on BC and serve as a therapeutic target for BC treatment.
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Objective:To explore leuncine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) expression in oral verrucous carcinoma(OVC) and its possible mechanism of tumor suppression.Methods:Paraffin specimens of OVC (n =15) and oral squamous cell carcinoma(OSCC,n =30) and corresponding adjacent normal tissues,and 15 normal mucosa tissues(NM) as control from injured patients were collected.The expression levels of LRIG1 and Bcl-2 were examined using immunohistochemical SP method.The correlation between the expression levels of LRIG1 and Bcl-2 was determined using two tailed Pearson's correlation.Results:LRIG1 was significantly lower in OVC tissue than that in NM tissue,but higher than in OSCC tissue.The expression levels of Bcl-2 in OVC were significantly higher than that in NM,but lower than in OSCC.The expression level of LRIG1 was negatively correlated with expression level of Bcl-2 in NM,OVC and OSCC tissue.Conclusion:LRIG1 may inhibit the expression of Bcl-2 and the development of OVC.
ABSTRACT
Pituitary adenomas (PAs) are well known as a common intracranial benign tumor, and a portion of PAs are refractory to current therapeutic methods. ErbB receptors family signaling pathway regulates the expression of PAs activation associated gene. Inhibition of epidermal growth factor receptor (EGFR) can inhibit proliferation of PAs. Leucine-rich repeats and immunoglobulin-like domains protein 1 ( LRIG1), a negative mediated gene of ErbB receptors family, plays a role in many tumors. However, there are seldom researches about the functional role of LRIG1 in PAs. The aim of this study is to explore the potential effect of LRIG1 and its regulating mechanism in PAs. First, we investigated the role of LRIG1 in cell migration, invasion of PAs with transfected LRIG1 or control. Then, we explored its impact on cell proliferation and apoptosis of PAs in vivo. To study the regulating mechanism of LRIG1, we examined the expression of molecular factor of PI3K/AKT and Ras/Raf/ERK pathway using Western blotting in vitro and RT-PCR in vitro and in vivo. It was found that LRIG1 over-expression inhibited cell migration, invasion and proliferation, and promoted apoptosis of PAs in vivo and in vitro. Furthermore, LRIG1 suppressed the expression of signaling of PI3K/AKT and Ras/Raf/ERK pathways in PAs. LRIG1, as a negative mediated gene of tumor, can inhibit biological function of PAs via inhibiting PI3K/AKT and Ras/Raf/ERK pathways, and it might be a new target for gene therapy of PAs.
Subject(s)
Animals , Female , Humans , Mice , Apoptosis , Genetics , Brain Neoplasms , Genetics , Pathology , Cell Line, Tumor , Cell Movement , Genetics , Cell Proliferation , Genetics , Gene Expression Regulation, Neoplastic , MAP Kinase Signaling System , Genetics , Membrane Glycoproteins , Genetics , Oncogene Protein v-akt , Phosphatidylinositol 3-Kinases , Genetics , Pituitary Neoplasms , Genetics , Pathology , Xenograft Model Antitumor Assays , raf Kinases , GeneticsABSTRACT
PURPOSE: Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) are an inhibitor of receptor tyrosine kinases (RTKs) that was discovered in recent years, and many studies showed that LRIG1 is a tumor suppressor gene and may be related to tumor drug resistance. In this study, we explored whether LRIG1 protein expression can improve the chemosensitivity of glioma cells and what was its mechanism. MATERIALS AND METHODS: We collected 93 cases of glioma tissues and detected the expression of LRIG1 and BCL-2. We constructed a multidrug resistance cell line U251/multidrug resistance (MDR) and examined the change of LRIG1 and BCL-2 at mRNA and protein expression levels. LRIG1 expression was upregulated in U251/MDR cells and we detected the change of multidrug resistance. Meanwhile, we changed the expression of LRIG1 and BCL-2 and explored the relationship between LRIG1 and BCL-2. Finally, we also explored the relationship between LRIG1 and RTKs. RESULTS: LRIG1 was negatively correlated with BCL-2 expression in glioma tissue and U251/MDR cells, and upregulation of LRIG1 can enhance chemosensitivity and inhibit BCL-2 expression. Furthermore, LRIG1 was negatively correlated with RTKs in U251/MDR cells. CONCLUSION: These results demonstrated that LRIG1 can improve chemosensitivity by modulating BCL-2 expression and RTK signaling in glioma cells.
Subject(s)
Humans , Astrocytoma/drug therapy , Cell Line, Tumor , Drug Resistance, Neoplasm/genetics , Gene Expression Regulation, Neoplastic , Gene Knockdown Techniques , Glioma/drug therapy , Membrane Glycoproteins/metabolism , Proto-Oncogene Proteins c-bcl-2/metabolism , RNA, Messenger/metabolism , Receptor Protein-Tyrosine Kinases/metabolismABSTRACT
The effects of RNAi-mediated gene silencing of LRIG1 on proliferation and invasion of the human glioma cell line U251-MG and the possible mechanisms were explored in this study.The plasmids pGenesi12-LRIG1-shRNA1 and pGenesi12-LRIGl-shRNA2 were transfected into U251-MG glioma cells respectively by using Lipofectamine 2000 and the transfected cells in which the LRIGI expression was stably suppressed were selected by G418.The cells transfected with negative shRNA served as control.The expression levels of LRIG1 mRNA and protein were measured by qRT-PCR and Western blotting,respectively.The cell cycle was analyzed by flow cytometry.The results showed that LRIG1 mRNA expression was reduced by 70％ and 58％ and LRIG1 protein expression by 58％ and 26％ in U251-MG cells transfected with pGenesil2-LRIGl-shRNAl and pGenesil2-LRIG1-shRNA2 relative to the negative shRNA-transfected U251-MG cells.The proliferative capacity of the LRIG1 specific siRNA-transfected cells was stronger than that of control cells.Cell cycle analysis showed that silencing LRIG 1 significantly increased the percentage of S phase cells and the proliferation index (P＜0.01).Moreover,silencing LRIG1 could promote the invasion of U251-MG cells (P＜0.05).These findings suggested that LRIG1-targeting siRNA can exert a dramatically inhibitory effect on RNA transcription and protein expression of LRIG1,and LRIG1down-regulation could promote the proliferation of U251-MG cells,arrest U251-MG cells in S phase,and enhance the invasion of U251-MG cells.
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The expression of epidermal growth factor receptor (EGFR) and leucine-rich repeats and immunoglobulinqike domain 1 (LRIG-1) in humantrigeminal neurinoma was investigated and their effect on the origination and development of trigeminal neurinoma, and the relationship between them was studied. By using immunohistochemistry with tissue chip, the expression of EGFR and LRIG-1 was detected in 23 cases of trigeminal neurinoma. It was found that in the 23 cases, the expression rate of EGFR was 21.74 %, while that of the LRIG-1 was 78.26 %. There was a negative correlation between them. It wassuggested that LRIG-1 might inhibit the malignant differentiation and proliferation of the trigeminal neurinoma possibly by the negative feedback loop of EGFR.
ABSTRACT
ObjectiveTo explore the molecular mechanism that LRIG1 inhibits signal transduction system of epidermal growth factor receptor(EGFR)by investigating the role of LRIG1 in glioma.MethodsThe plasmid pcDNA3.1-LRIG1 was transfected into primary glioma cells by Lipofectamine.Then,the changes of LRJG1 and EGFR in the transfected glioma cells were measured by RT-PCR and Western blot,and the cell proliferation and apoptosis were analyzed by MTT and flow cytometry.ResultsThe expression levels of LRIG1 mRNA and protein in the glioma cells transfected with pcDNA-LRIG1 were significantly higher than those of control group and pcDNA3.1 transfected glioma cells,while those of EGFR mRNA and protein were significantly lower.The expression of PKC? and Bax was up-regulated,while the expression of bcl-2 was down-regulated.The growth of glioma cells was inhibited and their apoptosis was obviously enhanced.ConclusionBy participating the construction of the negative feedback loop of EGFR,LRIG1 inhibits the occurrence and growth of tumor through several pathways.